Marine Weather Net

Straits of Florida from west end of Seven Mile Bridge to south of Halfmoon Shoal out 20 to 60 NM Marine Forecast





15 - 20


10 - 15

The Marine Weather Forecast In Detail:
GMZ074 Forecast Issued: 434 PM EDT Sat May 08 2021

Tonight...North To Northeast 5 To 10 Knots Early, Becoming East And Sharply Increasing To 15 To 20 Knots. Seas 1 To 3 Feet, Building To 3 To 5 Feet. Isolated Showers.
Sunday...East To Southeast Winds Near 15 Knots. Seas 3 To 4 Feet.
Sunday Night...East To Southeast Winds 15 To 20 Knots. Seas 3 To 6 Feet. Isolated Showers.
Monday...East To Southeast Winds Decreasing To 10 To 15 Knots. Seas Subsiding To 2 To 4 Feet.
Monday Night...East To Southeast Winds Increasing To Near 15 Knots. Seas 3 To 4 Feet.
Tuesday...East Winds 10 To 15 Knots. Seas 2 To 3 Feet.
Tuesday Night...East To Southeast Winds Near 15 Knots. Seas 2 To 4 Feet.
Wednesday...East Winds 10 To 15 Knots. Seas 2 To 3 Feet.
Wednesday Night...East To Southeast Winds Near 15 Knots. Seas 2 To 4 Feet. Isolated Showers.
Thursday...East Winds 10 To 15 Knots. Seas 2 To 3 Feet.
Thursday Night...East Winds 10 To 15 Knots. Seas 2 To 3 Feet. Isolated Showers.
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Synopsis for Keys coastal waters from Ocean Reef to Dry Tortugas: GMZ005
434 PM EDT Sat May 8 2021

High pressure will settle in across the western Atlantic with winds clocking around to the east and southeast through the overnight. Breezes will freshen tonight through Sunday night, before gradually slackening starting Monday through Wednesday.

Gulf Stream
The Approximate Shoreward Edge of the Gulf Stream as of May 08, 2021...
- 37 NM South of Dry Tortugas Light...on Loggerhead Key.
- 40 NM South of Cosgrove Shoal the Marquesas Keys.
- 33 NM South of Sand Key Key West.
- 20 NM South of Looe Big Pine Key.
- 15 NM South of Sombrero Key Marathon.
- 7 NM Southeast of Alligator Reef Islamorada.
- 5 NM Southeast of Molasses Reef Key Largo.
- 8 NM East of Carysfort Reef Ocean Reef.
Area Forecast Discussion
National Weather Service Key West FL
310pm EDT Sat May 8 2021

A persistent convergence zone has set up across the extreme southeast Florida and Upper Keys, which has sustained a couple of isolated showers and thunderstorms for the past couple hours. They have been very pulse-y in nature waxing and waning at times. Outside of this, there is no other precipitation detected. Likewise visible satellite shows mostly sunny skies across the remaining island communities.

Meanwhile, high pressure that was over the southeast U.S., is slowly emerging over the western Atlantic. As it does so, it is tightening the gradient across south Florida and the Florida Keys and inducing a surge. Currently it has made its way into the far eastern portions of our coastal waters.

.SHORT TERM (Tonight thorugh Tuesday night)... As the aforementioned high treks eastward and a thermal trough that is present across south Florida dissipates, the surge will spread west this evening. As such, breezy conditions will develop rather quickly from east to west, reaching the Lower Keys towards sunset. Dry air will also filter in as the high settles across the western Atlantic. Meanwhile, deep layer ridging will slowly return from the west. Aside from ongoing showers across the Upper Keys this afternoon, rain chances will fall below climatology through the period as a result.

Otherwise, high pressure will remain in control across the area, maintaining east to southeast winds. Expect above normal temperatures to prevail.

.LONG TERM (Wednesday through Friday)... High pressure across the western Atlantic will retreat eastward, with a ridge axis extending back across the FL Peninsula and across the eastern Gulf of Mexico initially. Beyond Wednesday there are some model discrepancies. They do however agree on a trough moving across the Great Lakes region, which will weaken and push the ridge east by Thursday. At the surface a large and sloppy high pressure will move out of the Central Plains and move east. Where this goes is where the differences lie. Generally expecting the high to build south across the FL Peninsula as it treks east. Where it ultimately settles will have implications on our PoPs. Overall, our winds will become northeast or east as the high builds south. Due to the uncertainties, have lowered Probability of Precipitation to 10 percent for the extended period. Should we get a prolonged period of northeast winds, we could see cloud lines develop towards the end of next week, which would increase our rain chances.

High pressure is emerging over the western Atlantic this afternoon. This is leading to freshening northeast to east breezes across the far eastern waters. As such, the waters off the Upper Keys are under a Small Craft Exercise Caution (SCEC) headline. Elsewhere, north to northeast gentle breezes will quickly clock around and sharply increase as the surge pushes west across the remaining waters. Therefore, all waters will have a SCEC headline going into effect for this evening and overnight. High pressure will then slowly trek east with east to southeast breezes. Expect peaks and lulls through Sunday night with additional SCEC headlines likely Sunday night. Thereafter, breezes gradually slacken starting Monday and continuing through Thursday.

In 2016, the daily record low temperature of 63F was recorded in Key West. This is also tied as the coldest temperature ever recorded in May. Temperature records date back to 1872.

NOAA Key West FL Office: Watches - Warnings - Advisories
FL...None. GM...None.